1. Technical Field
The present invention relates to a screen, a projector, and an image display device.
2. Related Art
The left-right direction mentioned in the present application is that viewed from the observer.
A screen for rear projection type projector generally has a two-layer configuration including a Fresnel lens sheet that collimates the direction of incident light to obtain emission light, and a lenticular lens sheet (diffusion lens sheet) that diffuse emission light from this Fresnel lens sheet in a left-right direction (horizontal direction) of the screen. This configuration leads to problems such as scintillation, where laser beams emitted from the same light source interfere with each other on the screen, or generation of a phenomenon known as speckling. Accordingly, screens are proposed for alleviating this interference (see for example Japanese Unexamined Patent Publication No. 2003-262920 and 2002-543455).
A rear projection type projector described in JP-A-2003-262920 includes a projection type display device arranged in a casing, a reflecting mirror that reflects projection light from the projection type display device, and a transparent screen that receives the projection light and displays an image. A flat actuator is provided on a rear face of the reflecting mirror, enabling speckling over the entire transparent screen to be reduced by making the flat actuator vibrate.
A projection type display described in JP-T-2002-543455 includes a light valve, a folding mirror, a projecting mirror, and a projection screen; processing of speckles on the screen being performed by making one of these vibrate at a frequency that is high enough to be invisible to a user.
However, the rear projection type projector described in JP-A-2003-262920 reduces scintillation only in the optical system that projects the image onto the screen and does not deal with interference generated on the screen where the image is formed, making it difficult to suppress scintillation reliably.
Furthermore, in the projection type display described in JP-T-2002-543455, since the projection screen is merely vibrated by, for example, mechanical unit, the image also moves, and this causes problems such as wobbling in the horizontal direction of the image as viewed by an observer, and wobbling of the focal point.